The present disclosure relates to semiconductor manufacturing, and more particularly to a method of spalling, i.e., removing, a material layer portion from a base substrate utilizing at least one stressor layer portion that is formed atop a base substrate.
Devices that can be produced in thin-film form have three clear advantages over their bulk counterparts. First, by virtue of less material used, thin-film devices ameliorate the materials cost associated with device production. Second, low device weight is a definite advantage that motivates industrial-level effort for a wide range of thin-film applications. Third, if dimensions are small enough, devices can exhibit mechanical flexibility in their thin-film form. Furthermore, if a device layer is removed from a substrate that can be reused, additional fabrication cost reduction can be achieved.
Efforts to (i) create thin-film substrates from bulk materials (i.e., semiconductors) and (ii) form thin-film device layers by removing device layers from the underlying bulk substrates on which they were formed are ongoing. The controlled surface layer removal required for such applications has been successfully demonstrated using a process known as spalling; see U.S. Patent Application Publication No. 2010/0311250 to Bedell et al. Spalling includes depositing a stressor layer on a substrate, placing an optional handle substrate on the stressor layer, and inducing a crack and its propagation below the substrate/stressor interface. This process, which is performed at room temperature, removes a thin layer from the entire surface of the base substrate. By thin, it is meant that the layer thickness is typically less than 100 microns, with a layer thickness of less than 50 microns being more typical.